//Given the root of a binary tree and an integer targetSum, return all root-to-l
//eaf paths where each path's sum equals targetSum. 
//
// A leaf is a node with no children. 
//
// 
// Example 1: 
//
// 
//Input: root = [5,4,8,11,null,13,4,7,2,null,null,5,1], targetSum = 22
//Output: [[5,4,11,2],[5,8,4,5]]
// 
//
// Example 2: 
//
// 
//Input: root = [1,2,3], targetSum = 5
//Output: []
// 
//
// Example 3: 
//
// 
//Input: root = [1,2], targetSum = 0
//Output: []
// 
//
// 
// Constraints: 
//
// 
// The number of nodes in the tree is in the range [0, 5000]. 
// -1000 <= Node.val <= 1000 
// -1000 <= targetSum <= 1000 
// 
// Related Topics 树 深度优先搜索 
// 👍 499 👎 0


package leetcode.editor.cn;

import java.util.ArrayList;
import java.util.List;

//Java：Path Sum II
class P113PathSumIi {
    public static void main(String[] args) {
        Solution solution = new P113PathSumIi().new Solution();
        // TO TEST
        TreeNode root = new TreeNode(-2);
        root.right = new TreeNode(-3);
        System.out.println(solution.pathSum(root, -5));
    }
    //leetcode submit region begin(Prohibit modification and deletion)

    /**
     * Definition for a binary tree node.
     * public class TreeNode {
     * int val;
     * TreeNode left;
     * TreeNode right;
     * TreeNode() {}
     * TreeNode(int val) { this.val = val; }
     * TreeNode(int val, TreeNode left, TreeNode right) {
     * this.val = val;
     * this.left = left;
     * this.right = right;
     * }
     * }
     */
    class Solution {
        public List<List<Integer>> pathSum(TreeNode root, int targetSum) {
            return pathSum(root, 0, targetSum, new ArrayList<>());
        }

        private List<List<Integer>> pathSum(TreeNode root, int currentSum, int targetSum, List<Integer> path) {
            List<List<Integer>> result = new ArrayList<>();
            if (root == null) {
                return result;
            }
            int val = root.val;
            path.add(root.val);
            currentSum += val;
            if (root.left == null && root.right == null) {
                if (currentSum == targetSum) {
                    result.add(new ArrayList<>(path));
                    return result;
                }
            }
            if (root.left != null) {
                result.addAll(pathSum(root.left, currentSum, targetSum, path));
                path.remove(path.size() - 1);
            }
            if (root.right != null) {
                result.addAll(pathSum(root.right, currentSum, targetSum, path));
                path.remove(path.size() - 1);
            }
            return result;
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}